Allow URLs without http:// in non-user comments

Almost all blogs and web sites I have seen which allow a poster to enter their home page allow that entry to be without an http:// on the front. They just detect if a URL class is present and add http:// if it is not, then do the sanity check. Drupal is rare in insisting on it being fully qualified, and my commenters complain to me about this.

The patch is simple, just insert some code in comment.module before if (!valid_url($edit['homepage'], TRUE)) { to check if $edit['homepage'] has a URI type at the front, and add http:// if it doesn't.